Efficacy of Nijmegen Questionnaire in recognition of the hyperventilation syndrome

The pattern of complaints of patients with the hyperventilation syndrome (HVS) was studied on the basis of the Nijmegen HVS Questionnaire (van Doorn, Colla, Folgering). This list was completed by 75 patients with the clinical diagnosis HVS. Non-metric principal components analysis (NMPCA) showed that the structure was three-dimensional, the dimensions being labelled: Shortness of breath (HVS-1), Peripheral tetany (HVS-II), Central tetany (HVS-III). The questionnaire's differentiating ability was investigated by comparing HVS patients with non-HVS persons (80 persons employed in health care). All three components had an unequivocally high ability to differentiate between HVS and non-HVS. Application of linear analysis of discriminance to HVS-I, HVS-II and HVS-III together yielded 93% correct classifications. Statistical double cross-validation resulted in 90 and 94% correct classifications. The sensitivity of the Nijmegen Questionnaire in relation to the clinical diagnosis was 91% and the specificity 95%. It is concluded that the questionnaire is suitable as a screening instrument for early detection of HVS, and also as an aid in diagnosis and therapy planning.

Response to hyperventilation and inhalation of 5.5% carbon dioxide-enriched air across the DSM-III—R anxiety disorders

Anxiety disorder patients (n = 198; under criteria of the Diagnostic and Statistical Manual of Mental Disorders; rev. 3rd ed.; American Psychiatric Association, 1987) and nonanxious control subjects (n = 25) underwent challenges of 90 s of voluntary hyperventilation and 15 min of 5.5% carbon dioxide in air. Panic disorder subjects showed a greater subjective response to both challenges than did subjects with other anxiety disorders, who in turn responded more than did control subjects. Furthermore, subjects with panic disorder as an additional diagnosis tended to report more subjective response than did anxiety disorder subjects without panic disorder. The best prechallenge predictor of response to each procedure was a measure of fear of physical symptoms. The findings support previous results that have pointed to a greater fear or anxiety-inducing effect of these challenge procedures in panic disorder patients, as compared with other subjects.

Fear of physical sensations and trait anxiety as mediators of the response to hyperventilation in nonclinical subjects

Three studies were conducted to compare the ability of a measure of fear of physical sensations (Anxiety Sensitivity Index; ASI) and a measure of trait anxiety (State-Trait Anxiety Inventory; STAI) to predict response to hyperventilation. In the first study subjects (N = 43) were selected who differed in scores on the ASI but were equated on levels of trait anxiety. Two other studies were conducted in which subjects (ns = 63 and 54) varied randomly on ASI and STAI scores. The results indicate that scores on the ASI account for a significant proportion of variance in the response to hyperventilation that is not accounted for by scores on the STAI.

Prevalence of dysfunctional breathing in patients treated for asthma in primary care: cross sectional survey

OBJECTIVES

To estimate the prevalence of dysfunctional breathing in adults with asthma treated in the community.

DESIGN

Postal questionnaire survey using Nijmegen questionnaire.

SETTING

One general practice with 7033 patients.

PARTICIPANTS

All adult patients aged 17-65 with diagnosed asthma who were receiving treatment.

MAIN OUTCOME MEASURE

Score >/=23 on Nijmegen questionnaire.

RESULTS

227/307 patients returned completed questionnaires; 219 (71.3%) questionnaires were suitable for analysis. 63 participants scored >/=23. Those scoring >/=23 were more likely to be female than male (46/132 (35%) v 17/87 (20%), P=0.016) and were younger (mean (SD) age 44.8 (14.7) v 49.0 (13.8, (P=0.05). Patients at different treatment steps of the British Thoracic Society asthma guidelines were affected equally.

CONCLUSIONS

About a third of women and a fifth of men had scores suggestive of dysfunctional breathing. Although further studies are needed to confirm the validity of this screening tool and these findings, these prevalences suggest scope for therapeutic intervention and may explain the anecdotal success of the Buteyko method of treating asthma.

Persistent respiratory irregularity in patients with panic disorder

BACKGROUND

Dysregulated respiratory control may play a role in the pathophysiology of panic disorder. This could be due to abnormalities in brain stem respiratory nuclei or to dysregulation at higher brain levels. Results from previous studies using the doxapram model of panic have yielded an unclear picture. A brief cognitive manipulation reduced doxapram-induced hyperventilation in patients, suggesting that higher level inputs can substantially alter their respiratory patterns. However, respiratory abnormalities persisted, including a striking irregularity in breathing patterns.

METHODS

To directly study respiratory irregularity, breath-by-breath records of tidal volume (V(t)) and frequency (f) from previously studied subjects were obtained. Irregularity was quantified using von Neumann's statistic and calculation of "sigh" frequency in 16 patients and 16 matched control subjects. Half of each group received a standard introduction to the study and half received a cognitive intervention designed to reduce anxiety/distress responses to the doxapram injection.

RESULTS

Patients had significantly greater V(t) irregularity relative to control subjects. Neither the cognitive intervention nor doxapram-induced hyperventilation produced significant changes in V(t) irregularity. The V(t) irregularity was attributable to a sighing pattern of breathing that was characteristic of panic patients but not control subjects. Patients also had somewhat elevated f irregularity relative to control subjects.

CONCLUSIONS

The irregular breathing patterns in panic patients appear to be intrinsic and stable, uninfluenced by induced hyperventilation or cognitive manipulation. Further study of V(t) irregularity and sighs are warranted in efforts to localize dysregulated neural circuits in panic to brain stem or midbrain levels.

Learning to have psychosomatic complaints: conditioning of respiratory behavior and somatic complaints in psychosomatic patients

OBJECTIVE

Assuming a subjective similarity between the experience of a hyperventilation episode and inhaling CO2-enriched air, we tested whether a respiratory challenge in association with a particular stimulus could result in altered respiratory behavior and associated somatic complaints upon presenting the stimulus only.

METHOD

Psychosomatic patients (N = 28) reporting hyperventilation complaints participated in a differential conditioning paradigm using odors with a positive or negative valence as conditioned stimuli (CS+ or CS-) and 7.4% CO2-enriched air as the unconditioned stimulus (US). Three CS+ and three CS-acquisition trials were run. During the test phase, two CS(+)- and two CS(-)-only trials were run, followed by two new test odors (with a positive or negative valence). Respiratory frequency, tidal volume, end-tidal fractional concentration of CO2, and heart rate were measured throughout the experiment. Somatic complaints were registered after each trial.

RESULTS

We observed a) increased respiratory frequency and an elevated level of somatic complaints upon presenting the CS+ only; b) a selective association effect: conditioning was only apparent with the negatively valenced CS+ odor; (c) no generalization of respiratory responses and complaints to the new odors; (d) no conditioning effect on dummy complaints that are usually not reported when inhaling CO2; (e) in exploratory comparisons with normal subjects, stronger conditioning effects on typical hyperventilation complaints in patients, and, in female subjects, on respiratory frequency.

CONCLUSION

Respiratory responses and psychosomatic complaints can be elicited by conditioned stimuli in a highly specific way. The findings are relevant for disorders in which respiratory abnormalities and/or psychosomatic complaints may play a role and for multiple chemical sensitivity.

Treatment of panic disorder with agoraphobia: comparison of fluvoxamine, placebo, and psychological panic management combined with exposure and of exposure in vivo alone

OBJECTIVE

The purpose of this comparative outcome study was to investigate whether the effects of exposure in vivo treatment for panic disorder with agoraphobia could be enhanced by adding interventions specifically for panic attacks before the start of exposure treatment. The additional effect of two types of treatment for panic attacks--pharmacological (fluvoxamine) and psychological (repeated hyperventilation provocations and respiratory training)--was examined. Thus, the combined treatment of panic interventions with exposure in vivo could be compared to exposure in vivo alone.

METHOD

Ninety-six patients were randomly assigned to four treatment conditions: double-blind, placebo-controlled fluvoxamine followed by exposure in vivo, psychological panic management followed by exposure, and exposure in vivo alone. Outcome was assessed by self-report measures, a standardized multitask behavioral avoidance test, and continuous monitoring of panic attacks. Seventy-six patients completed the study.

RESULTS

All four treatments were effective and resulted in a significant decrease of agoraphobic avoidance. Moreover, the combination of fluvoxamine and exposure in vivo demonstrated efficacy superior to that of the other treatments and had twice as large an effect size (difference between pre- and posttreatment scores) on self-reported agoraphobic avoidance. The other treatments did not differ among each other in effectiveness.

CONCLUSIONS

Results of the study indicate that the short-term outcome of exposure in vivo treatment can be enhanced by adding fluvoxamine treatment. Psychological panic management combined with exposure was not superior to exposure alone of equal duration.

Respiratory and psychiatric abnormalities in chronic symptomatic hyperventilation

Many physicians believe that the hyperventilation syndrome is invariably associated with anxiety or undiagnosed organic disease such as asthma and pulmonary embolus, or both. Twenty one patients referred by specialist physicians with unexplained somatic symptoms and unequivocal chronic hypocapnia (resting end tidal Pco2 less than or equal to 4 kPa (30 mm Hg) on repeated occasions during prolonged measurement) were investigated. All but one complained of inability to take a satisfying breath. Standard lung function test results and chest radiographs were normal in all patients, but histamine challenge showed bronchial hyper-reactivity in two of 20 patients tested, and skin tests to common allergens were positive in three of 18. Ventilation-perfusion scanning was abnormal in a further three of 15 patients studied, with unmatched perfusion defects in two and isolated ventilation defects in one. None of the 21 had thyrotoxicosis, severe coronary heart disease, or other relevant cardiovascular abnormalities. Ten of the 21 patients were neurotic and suffered from chronic psychiatric disturbance characterised by anxiety, panic, and phobic symptoms. The remainder had no detectable psychiatric disorders but reported proportionately more somatic than anxiety symptoms. Severe hyperventilation can occur in the absence of formal psychiatric or detectable respiratory or other organic abnormalities. Asthma and pulmonary embolus must be specifically excluded.

Slow recovery from voluntary hyperventilation in panic disorder

OBJECTIVE

Because hyperventilation has figured prominently in theories of panic disorder (PD) but not of social phobia (SP), we compared predictions regarding diagnosis-specific differences in psychological and physiological measures before, during, and after voluntary hyperventilation.

METHOD

Physiological responses were recorded in 14 patients with PD, 24 patients with SP, and 24 controls during six cycles of 1-minute of fast breathing alternating with 1 minute of recovery, followed by 3 minutes of fast breathing and 10 minutes of recovery. Speed of fast breathing was paced by a tone modulated at 18 cycles/minute, and depth by feedback aimed at achieving an end-tidal pCO2 of 20 mm Hg. These values were reached equally by all groups.

RESULTS

During fast breathing, PD and SP patients reported more anxiety than controls, and their feelings of dyspnea and suffocation increased more from baseline. Skin conductance declined more slowly in PD over the six 1-minute fast breathing periods. At the end of the final 10-minute recovery, PD patients reported more awareness of breathing, dyspnea, and fear of being short of breath, and their pCO2s, heart rates, and skin conductance levels had returned less toward normal levels than in other groups. Their lower pCO2s were associated with a higher frequency of sigh breaths.

CONCLUSIONS

PD and SP patients report more distress than controls to equal amounts of hypocapnia, but PD differ from SP patients and controls in having slower symptomatic and physiological recovery. This finding was not specifically predicted by hyperventilation, cognitive-behavioral, or suffocation alarm theories of PD.

Double-blind placebo-controlled study of the hyperventilation provocation test and the validity of the hyperventilation syndrome

BACKGROUND

Hyperventilation syndrome (HVS) describes a set of somatic and psychological symptoms thought to result from episodic or chronic hyperventilation. Recognition of symptoms during the hyperventilation provocation test (HVPT) is the most widely used criterion for diagnosis of HVS. We have investigated the validity of the HVPT and of the concept of HVS.

METHODS

In a randomised, double-blind, crossover design, the ability of 115 patients with suspected HVS to recognise symptoms during the HVPT was compared with the ability to recognise symptoms during a placebo test (isocapnic overbreathing, with carbon dioxide levels maintained by manual titration). 30 patients who had positive results on the HVPT underwent ambulatory transcutaneous monitoring of pCO2 to ascertain whether they hyperventilated during spontaneous symptom attacks.

FINDINGS

Of the 115 patients who underwent the HVPT and the placebo test, 85 (74%) reported symptom recognition during the HVPT (positive diagnosis HVS). Of that subset, 56 were also positive on the placebo test (false-positive), and 29 were negative on the placebo test (true-positive). False-positive and true-positive patients did not differ in symptom profile or in physiological variables. During ambulatory monitoring (15 true-positive, 15 false-positive) 22 attacks were registered. Transcutaneous end-tidal, pCO2 decreased during only seven. The decreases were slight and apparently followed the onset of the attack, which suggests that hyperventilation is a consequence rather than a cause of the attack. There were no apparent differences between false-positive and true-positive patients.

INTERPRETATION

The HVPT is invalid as a diagnostic test for HVS. Hyperventilation seems a negligible factor in the experience of spontaneous symptoms. The term HVS should be avoided.

Respiratory biofeedback-assisted therapy in panic disorder

The authors describe a new methodologically improved behavioral treatment for panic patients using respiratory biofeedback from a handheld capnometry device. The treatment rationale is based on the assumption that sustained hypocapnia resulting from hyperventilation is a key mechanism in the production and maintenance of panic. The brief 4-week biofeedback therapy is aimed at voluntarily increasing self-monitored end-tidal partial pressure of carbon dioxide (PCO2) and reducing respiratory rate and instability through breathing exercises in patients' environment. Preliminary results from 4 patients indicate that the therapy was successful in reducing panic symptoms and other psychological characteristics associated with panic disorder. Physiological data obtained from home training, 24-hour ambulatory monitoring pretherapy and posttherapy, and laboratory assessment at follow-up indicate that patients started out with low resting PCO2 levels, increased those levels during therapy, and maintained those levels at posttherapy and/or follow-up. Partial dissociation between PCO2 and respiratory rate questions whether respiratory rate should be the main focus of breathing training in panic disorder.

Dyspneic-fear and catastrophic cognitions in hyperventilatory panic attacks

The tenability of cognitive explanations of the experience of fear during panic attacks (viz. Ley's misattribution-of-symptoms hypothesis and Beck's and Clark's catastrophic-misinterpretation-of-symptoms hypotheses) is seriously questioned by findings from three independent lines of research: (a) Wolpe and Rowan's observation that catastrophic cognitions follow fear, (b) Rachman, Levitt and Lopatka's reports of panic attacks without fearful cognitions, and (c) reports of panic attacks during sleep occurring predominately during non-dreaming stages of sleep. Recognition of these findings led Ley to reject his misattribution-of-symptoms hypothesis in favor of an innate emotional-respiratory-response explanation. The revised hyperventilation theory now maintains that fear experienced during a hyperventilatory panic attack is caused by severe dyspnea in the context of little or no perceived control over the causes of the dyspnea (i.e. dyspneic-fear). Cognitions during panic attacks are discussed in terms of the cognitive deficit that results from the cerebral hypoxia produced by hyperventilation. Implications for theory and treatment are discussed.

Anxiety sensitivity and history of panic as predictors of response to hyperventilation

In this study, we examined the effects of anxiety sensitivity on the response to hyperventilation in college students with and without a history of spontaneous panic attacks. Reiss et al.'s (Behav. Res. Ther. 24, 1-8, 1986) Anxiety Sensitivity Index and Norton et al.'s (Behav. Ther. 17, 239-252, 1986) Panic Attack Questionnaire were used to select Ss. Following five min of voluntary hyperventilation, high anxiety sensitivity Ss reported more anxiety and more hyperventilation sensations than did low anxiety sensitivity Ss. A history of panic was only associated with enhanced responding to hyperventilation in Ss with high anxiety sensitivity; low anxiety sensitivity Ss who had experience with panic were no more responsive than low anxiety sensitivity Ss who had never had a panic attack. These findings suggest that high anxiety sensitivity may be a crucial determinant of panic attacks provoked by biological challenges (e.g. hyperventilation, sodium lactate infusion).

A controlled study of a breathing therapy for treatment of hyperventilation syndrome

A therapy directed toward slowing and regularizing the ventilatory pattern was compared with a partial-treatment, comparison procedure for individuals with somatic and psychological symptoms attributable to hyperventilation episodes (i.e. hyperventilation syndrome). Comparing repeated measures between a pretreatment baseline session and a post-treatment followup, we found that the experimental therapy, in contrast to the comparison procedure, produced a greater number of, and more extensive, improvements in psychological, symptom complaint and ventilatory dimensions. Results also suggest changes in central respiratory control mechanisms as a consequence of treatment.

Affective responses to hyperventilation: a test of the cognitive model of panic

A cognitive explanation of the association between acute hyperventilation and panic attacks has been proposed: the extent to which sensations produced by hyperventilation are interpreted in a negative and catastrophic way is said to be a major determinant of panic. Non-clinical subjects were provided with a negative or a positive interpretation of the sensations produced by equivalent amounts of voluntary hyperventilation. As predicted, there was a significant difference between positive and negative interpretation conditions on ratings of positive and negative affect. Subjects in the positive interpretation condition experienced hyperventilation as pleasant, and subjects in the negative interpretation condition experienced hyperventilation as unpleasant, even though both groups experienced similar bodily sensations and did not differ in their prior expectations of the affective consequences of hyperventilation. When the subjects were given a positive interpretation, the number of their sensations correlated with positive affect; when a negative interpretation was given, the number of bodily sensations correlated with negative affect. The results provide support for a cognitive model of panic and are inconsistent with the view that panic is simply a symptom of hyperventilation syndrome.

Hyperventilation and anxiety in panic disorder, social phobia, GAD and normal controls

Patients with DSM-III Agoraphobia, Panic Disorder, GAD, Social Phobia and normal controls underwent a series of experimental procedures and measures to determine whether panic attack patients show a greater tendency towards hyperventilation that is independent from their anxiety levels. Contrary to expectations, the Agoraphobia and Panic Disorder patients did not show significantly lower levels of expired pCO2 at rest than the other anxious or non-anxious groups. However, the panic attack patients did show significantly higher levels of anxiety and hyperventilatory symptoms during a hyperventilation test and during breathing 5% CO2 in air. A strong relationship was found between hyperventilatory symptoms and anxiety in all groups of patients and in the controls. On the basis of these results it was concluded that Agoraphobia and Panic Disorder patients do not show a unique tendency toward hyperventilation, but rather that their hyperventilatory symptoms and perhaps intermittent overbreathing episodes are a function of the high levels of anxiety they experience.

A treatment outline for agoraphobia. The Quality Assurance Project

The Royal Australian and New Zealand College of Psychiatrists has initiated a project to develop treatment outlines for various psychiatric disorders. It is envisaged that the present outline, which was developed by a project team and an expert committee may be modified by the College before being used in post graduate and continuing education and in peer review. In its present form it should be of use to practising psychiatrists. Comments and criticisms on this outline are welcome. A loose-leaf insert is included so that interested readers may respond, either directly to the project team or indirectly via the Editor. This is the first of a series of treatment outlines and concerns the diagnosis and treatment of agoraphobia. The next outline will be on the treatment of depressive illness.

Distinctions between panic disorder and generalised anxiety disorder: clinical presentation

Thirty-eight panic disorder and 48 generalised anxiety disorder subjects were asked to complete a number of questionnaires aimed at developing a general clinical picture of the two disorders. The results indicated that panic disorder is characterised by a sudden onset around the mid- to late-20s age group and is distinguished by symptoms which are chiefly hyperventilatory in nature and are accompanied by thoughts of serious physical or mental illness. Generalised anxiety disorder is characterised by a gradual onset of symptoms. Somatic symptoms associated with this disorder are generally accompanied by a realisation that the symptoms are the result of anxiety and are harmless. The two groups did not appear to differ greatly on a number of other scales except that the generalised anxiety disorder subjects scored higher on measures of manifest anxiety and social phobia.

Diagnosis of hyperventilation syndrome on the basis of reported complaints

Four hundred consecutive patients referred for diagnosis of hyperventilation syndrome were studied to assess the utility of self-reported complaints for making primary diagnoses of the syndrome. One-half of the subjects were unequivocally diagnosed as positive for the disorder, the other half as negative. This diagnosis was determined by the presence or absence of two criteria with established validity: (a) recognition of major presenting symptoms during a period of voluntary hyperventilation, and (b) slow return of end-tidal CO2 levels to pre-hyperventilation baseline values after the voluntary period of overbreathing. Analyses focused on differences in presenting symptoms between those patients with and those without the syndrome. Results revealed many significant differences in frequency of specific complaints between groups. However, there was much overlap between groups with regard to all complaints. A discriminant analysis of the complaint items led to a correct classification of 66 per cent of the subjects. Our findings thus indicate that the risks of misclassification of hyperventilation syndrome are relatively large when diagnosis is solely based on presenting complaints. Consequently, reported symptoms characteristic of the disorder should be used as preliminary indications requiring further evaluation.